Abstract
A fire whirl is a kind of spinning flow accompanied by chemical changes. It has a combustion-enhancing effect, increasing the fire's heat release rate and may induce catastrophic consequences. However, the combustion characteristics of a fire whirl at dynamic pressure are still unknown. This experiment was conducted in a sizeable low-pressure chamber with dimensions of 3.0 m x 2.0 m x 2.0 m, in which a small-sized fire whirl was generated using a square vertical slot with variable slit width. The ambient pressure was reduced to the target pressure by the low-pressure chamber, and a dynamically pressurized environment was created by controlling the air inlet rate. This experiment investigates characteristic parameters such as combustion rate, heat radiation flux, and flame height of the fire whirl. The experimental results show that the flame height of the fire whirl with pressure changes as a result of the first increase and then maintains the same; the fire whirl has a pronounced combustion enhancement effect, and the combustion rate is about 3.5 times that of the ordinary pool fire; four walls open slit fire whirl combustion there is a "critical width," the closer the width, the higher the mass combustion rate, the more stable the flow field, the more the ratio between the burning rate and the characteristic length of the oil basin, the more the ratio between the dimensionless number and the Grashof number is close to a linear relationship. The heat radiation flux increases with increasing pressure, and there is a linear relationship between (Q(r)''/P-2)(1/4) and P-2/3, where (Q(r)'') is the flame radiation and P is the pressure.